Oscillation generator



Oct. 19, 1937. LlNDENBLAD 2,095,990

OSCILLATION GENERATOR Filed Feb. 16, 1935 MHZ/1,4703

INVENTOR. NILS E. LINDENBLAD F 7% wm,

ATTORNEY.

Patented Oct. 19, 1937 PATENT OFFHCE OSCILLATION GENERATOR Nils E.Lindenblad, Port Jefferson, N. Y., assignor to Radio Corporation ofAmerica, a corporation of Delaware Application February 16, 1935, SerialNo. 6,814

Claims.

My present invention relates to short wave oscillation generators andhas as its main object to provide an improved resonant line controlledoscillation generator making use of a linear tu- 5 bular frequencycontrolling element one half wave length long. This construction affordsthe advantage that the oscillator becomes inexpensive and simple toconstruct besides being highly efficient in operation.

A further object of my present invention is to provide an improvedmetering system for indicating optimum operation of an alternatingcurrent system and in particular a line controlled oscillationgenerator.

In the accompanying drawing, I have shown one way of carrying intoeffect the objects of my present invention, the drawing illustrating,diagrammatically, a push-pull oscillation generator whose frequency isstabilized and controlled by a resonant line substantially one half wavelength long at the desired operating frequency.

Turning to the drawing, the tubular hollow cylindrical line 2 issubstantially one half wave length long at a desired operatingfrequency. The line 2 is insulatedly mounted by the supports shownwithin the concentric tubular container 4 grounded by means of suitablegrounding connections diagrammatically illustrated at 6. The midpoint ofthe line 2 is connected to the shielding shell 4 through the grid leakand resistance combination 8. At points symmetrically opposite themidpoint Ill on the linear or substantially straight resonant line 2,such as the points or rings l2, M, are connected the grids l6, I8 ofvacuum tubes 29, 22. Vacuum tube 20 is also provided with a plate 24 andcathode 26, and vacuum tube 22 contains plate or anode 28 and cathode orfilament 3G. The cathodes are connected directly to ground, as shown, orthey may be fed through choke coils with heating current so that thecathodes fluctuate at a radio frequency potential with respect toground, or they may be connected together by means of the tubularcathode system described more fully in my United States Patent No.2,052,576, granted September 1, 1936, on copending application SerialNo. 603,- 310, filed April 5, 1932, in which event the oathodes willfluctuate out of phase and at some radio frequency potential withrespect to ground. Between the plates there is connected a tuned circuit32 having a lumped inductance 34 and a variable tuning condenser 36. Theplate circuit 32 may be replaced by a single looped conductor ofsufficient length, if desired, and this single loop having substantiallyuniformly distributed inductance and capacity may be shunted by a tuningcondenser.

Signal input energy may be applied through the transformer 4|] connectedin series with the plate voltage supply lead 42, and output energy maybetaken through blocking condensers M and fed through transmission line 46to a suitable radiating antenna, not shown.

Oscillation generation takes place primarily by virtue of interelectrodefeedback through the tubes 20, 22, correct grid bias being maintained bythe grid leak and condenser arrangement 8.

The resonant line 2, because of its linearity, simplifies constructionand coincident with that there is a saving in constructional costs ascompared to other forms of frequency controlling systems.

The line 2, and also the concentric cylinder 4 therefor, is preferablymade of a material of high conductivity, such as copper, and ispreferably made of fairly large diameter so as to be of low loss and asto make the power factor of the frequency controlling line 2 a minimum.The line 2 while preferably one half wave length long may be made anyodd number of half wave lengths long. For all practical purposes, I havefound that a half wave length linear line will prove highlysatisfactory.

To determine when the system is operating correctly, thethermogalvanometer 5B is provided. One side 52 of this galvanometer isgrounded as shown and the other is connected to a metallic stud 54frictionally or screw-threadedly or otherwise movable within theinsulating bushing 56. This thermogalvanometer will give a readingproportional to the line voltage or current, that is to say, to the linevoltage or current on the line 2. The stud 54 is moved with respect tothe line 2 such that a desired reading appears upon thethermogalvanometer when the system is operating properly. This desiredreading may be made a maximum deflection or some substantial deflectionof the thermogalvanometer. Once that reading has been determined, itwill only be necessary thereafter, in order to obtain proper operationof the system, to adjust the voltagesv supplied the tubes, the tuning ofthe plate circuit and the adjustment of the filament circuit until thesame current deflection appears in the thermogalvanometer 50.

It is to be distinctly understood that the term ground, as used in thespecification and appended claims, is intended to mean any point 55 orsurface of zero or relatively fixed radio frequency potential.

Having thus described my invention, what I claim is: V

1. An oscillation generation system comprising a straight linearfrequency controlling element having a length equal to a multiple ofhalf the fundamental wave, a pair of electron discharge devices, eachhaving a control grid and an anode, connections from said control gridsto points on said element which are symmetrically and oppositelydisposed with respect to the electrical center of said element, and aparallel tuned output circuit of inductance and capacitance connectedbetween said anodes.

2. An oscillation generation system comprising a straight linearfrequency controlling element having a length equal to half thefundamental wave, a pair of electron discharge devices, each having agrid, cathode and anode, a. connection between said cathodes and ground,and

connections from said grids to points on said 7 element which aresymmetrically located with respect, to the electrical center of saidelement, a circuit including a resistance from the electrical center ofsaid element to ground, and a tuned output. circuit coupled to saidanodes.

3. An oscillation generator system' comprising a low power factorstraight linear element having a length equal to an odd multiple ofonehalf the fundamental wave, and a pair of electron discharge deviceshaving their control electrodes connected to said linear element atpoints which are symmetrical with respect to the electrical center ormid-point thereof, and a tuned output circuit coupled to the anodes ofsaid electron discharge devices.

4. An oscillation generation system comprising a hollow, straight,linear, frequency controlling element having a length equal to amultiple of half the fundamental wave, a pair of electron dischargedevices each having an anode, cathode and a control electrode, aconnection from the electrical center of said frequency controllingelement to said cathodes, connections from said control electrodestopoints on said element which .are symmetrically located with respecttosaid electrical center, a parallel tuned circuit of inductance andcapacitance connected between said anodes, and means coupled to a pointon said inductance intermediate its ends for modulating the oscillationsproduced by said electron discharge devices.

5. A system in accordance with claim 3, including a grounded metallictube placed about said linear element to prevent undesired radiationtherefrom.

NILS E. LINDENBLAD.

